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/*  Timer_init()
 *
 *  This routine initializes a timer in efi68k's DP8570A TCP
 *
 *  Input parameters:  NONE
 *
 *  Output parameters:  NONE
 *
 *  NOTE: It is important that the timer start/stop overhead be
 *        determined when porting or modifying this code.
 *
 *  COPYRIGHT (c) 1989-1999.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.OARcorp.com/rtems/license.html.
 *
 *  $Id: timer.c,v 1.2 2001-09-27 12:00:03 chris Exp $
 */
 
 
#include <bsp.h>
 
rtems_boolean Timer_driver_Find_average_overhead;
 
extern rtems_isr Clock_isr();
 
void Timer_initialize( void )
{
  /* stop counter */
  *MSR = 0;
  *T0CR = 0;
 
  /*
   * Make sure isr is installed
   */
 
  set_vector( Clock_isr, TCP_ISR_LEVEL+24, 1);
 
  /* clear timer ISR count */
  Timer_interrupts = 0;
 
  /* load count (count down timer) */
  *MSR = 0;
  *T0_MSB = 0xff;
  *T0_LSB = 0xff;
 
  /* clear old interrupts */
  *MSR = T0;
 
  /* enable timer 0 interrupt */
  *MSR = RS;
  *ICR0 |= T0E;
 
  /*
     TSS = 1        starts the timer (timer resets on start)
     M1/0 = 0/1     rate generator
     C2/1/0 = 0/0/0 external clock (8MHz) (1/8 usec resolution)
     RD = 0         read data (latchs count)
     CHG = 0        hold
   */
  *MSR = 0;
  *T0CR = (TSS | M0);
}
 
/*
 *  The following controls the behavior of Read_timer().
 *
 *  FIND_AVG_OVERHEAD *  instructs the routine to return the "raw" count.
 *
 *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
 *  is usually deducted from the number returned.
 *
 *  LEAST_VALID is the lowest number this routine should trust.  Numbers
 *  below this are "noise" and zero is returned.
 */
 
#define AVG_OVERHEAD      0  /* It typically takes X.X microseconds */
                             /* (Y countdowns) to start/stop the timer. */
                             /* This value is in microseconds. */
#define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
 
/*
 * Return timer value in 1/2-microsecond units
 */
int Read_timer( void )
{
  rtems_unsigned16 clicks;
  rtems_unsigned32 total;
  rtems_unsigned32 msb, lsb;
 
 
  /*
   *  Read the timer and see how many clicks it has been since counter
   *  rolled over.
   */
 
  *MSR = 0;
  *T0CR |= RD;
  /* must read MSB first */
  msb = *T0_MSB;
  lsb = *T0_LSB;
  clicks = 0xffff - ((msb << 8) | lsb);
 
  /*
   *  Total is calculated by taking into account the number of timer overflow
   *  interrupts since the timer was initialized and clicks since the last
   *  interrupts.
   */
 
  total = (Timer_interrupts * 0x10000 + clicks + 4)/8; /* in micoseconds */
  /*                                            ^^^ round to nearest int */
 
  if ( Timer_driver_Find_average_overhead == 1 )
    return total;          /* in XXX microsecond units */
 
  if ( total < LEAST_VALID )
    return 0;            /* below timer resolution */
 
  return (total - AVG_OVERHEAD);
}
 
 
/*
 *  Empty function call used in loops to measure basic cost of looping
 *  in Timing Test Suite.
 */
 
rtems_status_code Empty_function(void)
{
    return RTEMS_SUCCESSFUL;
}
 
void Set_find_average_overhead(
  rtems_boolean find_flag
)
{
  Timer_driver_Find_average_overhead = find_flag;
}

Line No.	Rev	Author	Line
1	30	unneback	`/* Timer_init()`
2			`*`
3			`* This routine initializes a timer in efi68k's DP8570A TCP`
4			`*`
5			`* Input parameters: NONE`
6			`*`
7			`* Output parameters: NONE`
8			`*`
9			`* NOTE: It is important that the timer start/stop overhead be`
10			`* determined when porting or modifying this code.`
11			`*`
12			`* COPYRIGHT (c) 1989-1999.`
13			`* On-Line Applications Research Corporation (OAR).`
14			`*`
15			`* The license and distribution terms for this file may be`
16			`* found in the file LICENSE in this distribution or at`
17			`* http://www.OARcorp.com/rtems/license.html.`
18			`*`
19			`* $Id: timer.c,v 1.2 2001-09-27 12:00:03 chris Exp $`
20			`*/`
21
22
23			`#include <bsp.h>`
24
25			`rtems_boolean Timer_driver_Find_average_overhead;`
26
27			`extern rtems_isr Clock_isr();`
28
29			`void Timer_initialize( void )`
30			`{`
31			`/* stop counter */`
32			`*MSR = 0;`
33			`*T0CR = 0;`
34
35			`/*`
36			`* Make sure isr is installed`
37			`*/`
38
39			`set_vector( Clock_isr, TCP_ISR_LEVEL+24, 1);`
40
41			`/* clear timer ISR count */`
42			`Timer_interrupts = 0;`
43
44			`/* load count (count down timer) */`
45			`*MSR = 0;`
46			`*T0_MSB = 0xff;`
47			`*T0_LSB = 0xff;`
48
49			`/* clear old interrupts */`
50			`*MSR = T0;`
51
52			`/* enable timer 0 interrupt */`
53			`*MSR = RS;`
54			`*ICR0 \|= T0E;`
55
56			`/*`
57			`TSS = 1 starts the timer (timer resets on start)`
58			`M1/0 = 0/1 rate generator`
59			`C2/1/0 = 0/0/0 external clock (8MHz) (1/8 usec resolution)`
60			`RD = 0 read data (latchs count)`
61			`CHG = 0 hold`
62			`*/`
63			`*MSR = 0;`
64			`*T0CR = (TSS \| M0);`
65			`}`
66
67			`/*`
68			`* The following controls the behavior of Read_timer().`
69			`*`
70			`* FIND_AVG_OVERHEAD * instructs the routine to return the "raw" count.`
71			`*`
72			`* AVG_OVEREHAD is the overhead for starting and stopping the timer. It`
73			`* is usually deducted from the number returned.`
74			`*`
75			`* LEAST_VALID is the lowest number this routine should trust. Numbers`
76			`* below this are "noise" and zero is returned.`
77			`*/`
78
79			`#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */`
80			`/* (Y countdowns) to start/stop the timer. */`
81			`/* This value is in microseconds. */`
82			`#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */`
83
84			`/*`
85			`* Return timer value in 1/2-microsecond units`
86			`*/`
87			`int Read_timer( void )`
88			`{`
89			`rtems_unsigned16 clicks;`
90			`rtems_unsigned32 total;`
91			`rtems_unsigned32 msb, lsb;`
92
93
94			`/*`
95			`* Read the timer and see how many clicks it has been since counter`
96			`* rolled over.`
97			`*/`
98
99			`*MSR = 0;`
100			`*T0CR \|= RD;`
101			`/* must read MSB first */`
102			`msb = *T0_MSB;`
103			`lsb = *T0_LSB;`
104			`clicks = 0xffff - ((msb << 8) \| lsb);`
105
106			`/*`
107			`* Total is calculated by taking into account the number of timer overflow`
108			`* interrupts since the timer was initialized and clicks since the last`
109			`* interrupts.`
110			`*/`
111
112			`total = (Timer_interrupts * 0x10000 + clicks + 4)/8; /* in micoseconds */`
113			`/* ^^^ round to nearest int */`
114
115			`if ( Timer_driver_Find_average_overhead == 1 )`
116			`return total; /* in XXX microsecond units */`
117
118			`if ( total < LEAST_VALID )`
119			`return 0; /* below timer resolution */`
120
121			`return (total - AVG_OVERHEAD);`
122			`}`
123
124
125			`/*`
126			`* Empty function call used in loops to measure basic cost of looping`
127			`* in Timing Test Suite.`
128			`*/`
129
130			`rtems_status_code Empty_function(void)`
131			`{`
132			`return RTEMS_SUCCESSFUL;`
133			`}`
134
135			`void Set_find_average_overhead(`
136			`rtems_boolean find_flag`
137			`)`
138			`{`
139			`Timer_driver_Find_average_overhead = find_flag;`
140			`}`

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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libbsp/] [m68k/] [efi68k/] [timer/] [timer.c] - Blame information for rev 30